Improvement in speaking-telegraphs



T. A. EDISON. Speaking-Telegraph.

No. 203,015. Patented April 30, 1878.

i jd." F,

UNITED STATES PATENT OFFICE.

'.IHO MAS ,A. EDISON, OF MENLO PARK, INEW JERSEY, ASSIGNOR TO WEST- EBNUNION 'lllLllGRAPH COMPANY, OF NEW YORK, N. Y.

IMPROVEMENT IN SPEAKING-TELEGRAPHS.

Specilicntion forming purl. of Letters Patent N0. 203,015, dated April30, 1878; application tiled.

August 28, 1877.

To all whom zt 11i/ay concern.-

Be it known that I, TnonAs A. EDISON, of Menlo Park, in the county ofMiddlesex and State of New Jersey, have invented au Improvement inSpeaking-Telegraphs, of which the following is a specicatiom f Theobject of this invention is to transmit and reproduce the human voiceover telegraphic circuits.

The invent-ion, which is a modification of an application for patentfiled by me April 27, 1877, consists in the following particulars: 'Amouth-piece provided with a slot or hole to allow of the escape of theair ejected from the mouth in the act of making a hissingconsonant,'th11s preventing-'a bulging of the diaphragm, and at thesaine time increasing in a Surprising manner the movement of thediaphragm when such hissing` sounds are made.

The invent-ion further consists iu the employment of mica as adiaphragm. I have discovered that of many substances which are suitablefor diaphragms, it alone will give the greatest amplitude of vibrationwith'the least harmonical or extra sound; that it remains unaffected bythe heat and moisture of the mouth, and docs not get` out of adjustmentby stretching, like thi n substances that have heretofore been used fordiaphragms.

'lhe invention further consists in a yielding contact plate-springsecured to the diaphragm so as to allow the diaphragm to make its fullvibration while such spring is pressing against the' tension-regulatornextfreferred to.

The invention further consists in a ltensionrcgulat'r made of elasticfiber and electric .conducting material, whereby the resistance of thecircuit is decreased by the compression of the ber, bringing theconducting material into more intimate contact, or the resistance isincreased by the expansion of the fiber.

In my application No. 141, lled July 20, 1 S7 7, a piece of plumbagoisdescribed for varying the resistance by pressure, and I have shown apiece of plumbago arranged in front of a diaphragm operated by the humanvoice, and connected with the telegraphic line inl such a. manner thatwhen tl le diaphragm went outward it would cause pressure upon thepluinbago, and this would increase the electric wave in the circuit, andif the diaphragm was vibrated weakly a light pressure would be placed onthe plumbago, and a. weaker wave would be sent, thus producing waves ofa strength proportional to the tones of the voice. This does not give asperfect articulation as the tension-regulator I am about to describe,principally on account of the great difference in pressure, or greateramount of pressure required to effect a given change. I have discoveredthat if any fibrous material-such as silk, asbestus, cotton, wool,sponge, or feathers-be coated, by rubbing or otherwise, with with a.semi-conducting substance, such as plumbago, carbon in its conductingform, me-

tallic oxides, and'other conduct-ing material,

and such fiber be gathered intoy a tutt and placed in a circuit, it isvery sensitiv a to the slightest movement. I am enabled not only toobtain the regulation by the greater or less pressure, but also toincrease or decrease the extent of sn r'acecontact between the particlesof conducting or semi-conducting material that is associated with theber.

It is best to use fibers that are sp ringy, such as sponge or silk, soas to prevent the niaterials packing and the regulator losing itselasticity.

I prefer to use unspun silk ber, cut in lengths of about one-sixteenthof au inch, which are' then coated with plumbago by thorough rubi bing,or by using a mucilaginouspa'ste of plumbago, rubbing and thoroughlydrying, after which the fiber, with a little loose plumbago, is rolledinto a cigar shape, and retained by a. bindingiber ot' silk. I proposeto call these articulators or electric tension regulat-v ors.

Another method of inetallizing i-he ber which I propose tocmploy is tosoak the ber in a solution of 4nitrate of silver or other metallic salt,and reduce the metal to a metallic state upon the fiber by a suitablereducing agent, such as exposing the silk to the fumes of phosphorus,this process of m'etallization being well' known among clectroplat'ersfor causing non-conducting articles to becomeconduetors for receiving adeposit of metal-thereon.

The fiber may be moistcned with a semi- .conducting fluid, and operateiu precisely the same manner, the resistance being lessened bycompressing the fiber, and vice versa.

The electric tension-regulator f, I place between a conducting-spring,a, secured to the diaphragm b, and the conducting poin-t or plate c,secured to the adjusting-post d, and

.adjust it so that when the diaphragm is in a state of rest theregulator will remain in con-l tact with both a and e by pressure. Thistension-regulator may be employed in various electric instruments-suchas rheostats-fto regulate the electric current passing at a given placeaccording to the pressure exerted unen the mass of ber.

In the drawing, Figure 1 is a section of a transmitting -instrument withmy improvements applied thereto.. Fig. 2 is a modification of themouth-piece.

The line-circuit passes to the spring in the center of the diaphragm bythe platina foil e; thence through the articulator or tension-regulatorf and contact c to the` pillar B; thence to battery and earth or returnwire.

At the. distant station the line enters any suitablereceiving-instrument, which may be an electro-magnet secured to aresonant box or operating-diaphragm operated by the armature or otherdevice. Y y

The plate a is attached firmly to the mica diaphragm or tympan b bymaking small holes in the mica and soldering the plate to the mica, thesolderentering the holes and adhering by the roughness of the surfacesof such holes. When the diaphragm on the transmitter is in a state ofrest, the circuit is closed, anda constant but weak current passesthrough the circuit, thc tension regulator oering, say, two thousandohms resistance.

If the slightest sound is made near the mouth-piece, the diaphragm isset vibrating, and the fibrous regulator is compressed and expands ateach vibration, thereby increasing and decreasing its resistance manyohms, and

causing a rise and fall of tension within thecircuit, and these waves soproduced act upon the distant receiving-instrument, wh'en thesevibrations are reproduced.

I n speaking into the case h, or into the resonant-box of any telephone,there is diiiiculty in transmitting the sounds from consonants, becausethe hissing sound produces a pressure upon the diaphragm instead of avibration. I obviate this diiculty by an opening in the speaking-tubewith an edge or angle, .against which the hissing sound is directed, andwhich responds to such sound, and communicates the same to thediaphragm; and as this hissing sound, in prononncing some of theconsonante, passes downwardly from the'mouth, I

introduce a notch or orifice, at e', in the lower part of thespeaking-tube h., so that, the sound passing down through the slot andstriking the sharp edges of the slot, the hissing sounds are interceptedand cut and turned into vibrations, and these, acting upon thediaphragm, increase enormously the distinetness and volume of thehissing sounds at. the receivinginstrument.

In speaking-tubes where there is no slot the air ejected iupronouncinghissing consonants,

having no escape, -causes the diaphragm to 4 vbulge outward, and solessen the resistance of the circuit, and not transmitthe hissing soundsexcept when exceedingly loud. A large hole in the tube near thediaphragm prevents the bulging of the diaphragm; but it does notincrease the eect of the hissing sounds, but on the contrary weakensthem, as well as the vowel-sound.

It is obvious that many modifications of the mouth-piece maybe made s olong as the holes or slots are located so that their edges cut thehissing sounds for the purpose set forth. A tube with a hole or slot, i,having a sharp edge between the mouth-piece and diaphragm, as in Fig. 2,may be used. I have found that mica, owing toits being composed ofinnumerable layers of thin sheets, does not give a ringing sound orharmonics like most other substances which have equal strength,rgidness, &c., especially metals, and it is not aiiccted, except in anunimportant extent, by the heat and moisture from the mouth; neitherdoes it stretch like metal. All these properties are essential in aspeaking-telegraph for insuring permanency and absence of falsevibrations or harmonic responses, and for obtaining perfectarticulation.

Animal membranes are inconstant, and are too sensitive to heat andmoisture, and are constantly stretching. I use a spring in the center ofthe diaphragm, which is somewhat weaker than the diaphragm, and this isfor the purpose of allowing the diaphragm tohave a more free movement,the spring serving to take up by its elasticity the-effect of the suddencheck of the diaphragm when theiber has been compressed too greatly byloud speakig.

The adjusting-postd, by `reference, is m e so that the disk is breng ttoward the diaphragm withoutl being turned, so as to prevent disturbingthe broustension-regulator.

It is obvious that many devices (other than the mere pressure of thediaphragm against the conducting-fiber) ma;r be used to secure the ber.

I claim asmy invention-- 1. In an instrument for transmitting electricimpulses by sound, a diaphragm or tympan of mica, substantially as setforth.

2. In an instrument for transmitting electric impulses by sound,`thecombination, with a .diaphragm or tympan, of au electrictensionregulator of ber and' electric conducting ma terial,substantially as set forth.

3. An electric tension-regulator composed of elasticibrous and electricconducting material.

4. The combination, in an electric instrument actuated by sound, of adia hragn or tympan, a conductor, and an electr c tensionregulatorcomposed of elastic ber and electric conducting material.

5. The combination, with anl electric tension-regulator composed offiber and electric 'tympan of mica, of an electric conductoraud pins ofsolder passing into holes in the mica to secure said conductor,substantially as set forth. l

7. In an instrument for transmitting electric impulses by sound, aresonant case having an opening nea-r the mouthpiece, substantially asand for the purposes set forth.

8. In an instrument for transmitting and rcproducing the human voice orother sound, a closed telegraphic circuit containing a battery andcompressible elastic material operated by the sound, for increasing anddecreasing the resistance to the battery-cu rrent, substantiall y as Setforth.

Signed by me this 16th day oz August, A. D. 1877.

THOS. A. EDTSON.

Witnesses:

WILLIAM, G. Mo'r'r, Crus. H. Sm'rir.

